Tunnel kiln construction and method of operation



May 30, 1939. P. D'Hl DREssLER TUNNEL KILN CONSTRUCTION AND METHOD 0F OPERATION s sheets-sheer 1 Filed July 17, 1957 lNvENToR l We @Laad/JU f/a/z ATTORNEY Y May 30, 1939.

P. DH. DRESSLER TUNNEL KILN CNSTRUCTION AND METHOD OF OPERATION Filed July 17, 193'? 4& 0 ff/ 44 3 sheetssheet 2 lNVENTOR ATTORNEY PatentedvMay 30,1939

lUNITED l STATES PATENT OFFICE l TUNNEL KILN CONSTRUCTION AND METHOD OF OPERATION -Philip dHuc Dressler, Pittsburgh, Pa., assignor to Swindell Dressler Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Application July 17, 1937, serial No. 154,179

6 Claims.

The general object of the present invention isA an upper level more highly than the goods mov- Aing through the space at a lower level are heated. To prevent or minimize such nonuniformity in heating at diierent levels, various kiln atmosphere recirculating means and other special expedients, complicating the construction or operation of the kiln, have been used, or proposed, to equalize the goods heating at different levels. In accordance with the present invention, an approximation to uniformity in heating at different levels suiliciently close for practical purposes', is 'obtained without materially complicating the structure or operation of the kiln. `In a preferred form of construction of the improved kiln, the fuel used to heat the kiln is burned in combustion chambers located' at the opposite sides, and extending along the length,

of a high temperatureor heating section of the kiln, and the heating gases are passed into the goods space of the kiln partly through combustion chamber outlets adjacent the junction of the heating and preheating sections of the kiln, and partly through outletsmore remote from the preheating section. The last mentioned outlets are distributed along* the lengths of the combustion chambers, and are'arranged to deliver gases into the goods space adjacent the bottom Of the latter, so that the heating gases may pass upward in contact with the goods, and exert a greater heating effect on the goods adjacent the bottom f of the goods space than upon the goods adjacent the top of the latter.v The'heating gases thus introduced into the gas space are withdrawn in part, at least, from a' portion of the preheating section located at a substantial distance from the heating section, so that there is a substantial lonl gitudinal flow of heating gases through the preheating section 'of the goods space. My improvedy kiln includes adjustable dampers adjustable to regulate the relative amounts of heating gases discharged through the different outlets fro each combustion chamber.

When, as may sometimes b the case, the heating gases dischargedfrom the combustion chamy bers and passing into the preheat'ing .section of the kiln heat up the goods passing through the preheating section of the kiln more rapidly than l is desirable, I may temper or suitably lower the temperature of the heating gas and air mixture coming into contact with the goods in the preheating section, by introducing cold atmospheric air into the kiln chamber at the junction of ,the l0 heating and preheating sections.

The various features of novelty which'characterize the present invention are pointed out lwith particularity in the claims annexed t'o and forming a part of this specication. For a bet- 15 ter understanding of the invention, however, its advantages, and specific objects attained with its use, reference should be had to the accompanying drawingsand descriptive matter in whichI have illustrated and described a preferred em- 20 bodiient of the invention. x l Of theA drawings: l

Figs. 1 and 1a are somewhat diagrammatic plan sections of adjacent longitudinal portions of A. a continuous tunnel kiln, constructed in accord- 25 ance with the present invention;

Fig. 2' is a section, the left half of which is taken on the line 2-.2 of Fig. 1, and the right half ofA which is taken on the line 2A--2A of Fig. 1a; l ao' tions A, A2 and A3, respectively, extending in the order stated between the entrance and exit ends of the kiln. The bottom or iloor of the goods 40 space of the'kilnfis a movable goods advancing hearth, formed, in the kiln shown, by the platforms C of kiln cars having wheels C' running on the track rails B. Each kiln car C, as shown,

comprises a metallic understructure in which'the 45 car wheels C are mounted, a refractory body portion C2, girders C3 extending transversely of the can and supported on the body C2 and supporting the goods supporting' platform C of thecar. The girders C3 are spaced away from one 50 another to provide channels C4 extending horizontally through the carstructure between the body `C2 and platform C. Openings C5 in the car platforms C permit of circulation of the. kiln atmosphere between the goods space proper, of 55 nicate at their ends with the spaces between the side edges of the platform C and the adjacent stationary portions of the-kiln structure. As

shown, the kiln cars are of the usual type, andl for example, are like the cars shown in my prior Patent 1,521,216, granted Dec. 30, 1924. The car and kiln arrangement shown also follows the usual practice of the prior art in respect to the car and kiln carried means cooperating to maintain sand seals D, preventing gas flow at the sides of the cars, between the goods space of the kiln and the space beneath'the car bodies. At each side of the goods space, in, and extending for the full length of, the high temperature. section A2, and above the bench portion A4 of the kiln structure, is a combustion chamber E. At or adjacent its end remote from the entrance end of the kiln, each combustion chamber is provided with a fiuid fuel burner F, as shown an oil burner, and there may be one or more other burners F' opening to each combustion chamber at varying distances along its length. As yshown in Fig. 1a, each combustion chamber E is provided with two intermediate burners F. Ihe air for combustion may be air used inv cooling the goods passing through 4the cooling zone A3, and be thereby preheated prior to its delivery to a ue space A5 from each of which it passes ,to the adjacent combustion chamber E, at a rate regulated by' adjustment of a damper IF. The details of the burner fuel and air supply provisions need not be further illustrated or described as they form no part of the present invention.

'I'he relative amounts of the products of combustion discharged from each combustion chamber E through the corresponding port G, and through the corresponding ports H, is regulated and controlled by the adjustment of one or moredampers. For the purposes of such regulation,

each comb'ustion chamber will ordinarily be provided with a damper which, like the damper I l shown, is immediately adjacent the corresponding the dampers IF, I and IA for the insertion of a hook bar or other implement for adjusting the adjacent damper, and other side wall openings As are provided for the insertion of an implement for adjusting the dampers IB. The outer end of each opening Ai is normally closed, as by means of a. 'stopper brick A6'.

All of the products of combustion discharged from the combustion chamber E-through its ports G and I-I, flow longitudinally of the kiln into the preheating zone or section of the kiln goods space. From the latter, thel spent, or nearly spent, heating gases are withdrawn through distributed ports A'I into flues A8 formed in the side walls'of the kiln chamber and extending longitudinally of the preheating zone of the kiln. The distribution of inow into each ue A8 through the different ports A'I may be controlled by the-adjacent damper blocks A9. Each of the latter is accessible for aisaoec adjustment through a corresponding opening formed in the outer wall of the ue A8, and normally closed, as by means of a stopper block or brick A10. Heating gases are withdrawn from each flue, A8, through an uprising channelA11, communicating at its upper end with an offtake ue (not shown). The relative amounts of gas passing through the two' nues A8 may be controlled by the adjustment of dampers A!n in the vertical flues A11. As those skilled in the art will understand, the described preheating zone flue system described in this paragraph, is not novel herein, but, on the contrary, is of a type well known, and in extensive commercial use.

'I'he wall between each combustion chamber and the goods space of the kiln may take various forms. As shown in Figs. 1 and 2, the lower portion of each wall comprises a row of end to end ceramic bodies or'partitions h separating horizontal channels extending transversely of thev kiln length, and constituting the above mentioned ports H. The upper portion of the wall is formed by a row of side by side tiles e, each having its lower end resting on the portion of the wall-in which the ports H are formed. The tiles e areinclined to the vertical so that the upper end of each tile is more distant than the lower end from the central plane of the kiln. 'I'he upper ends of the tiles e rest against the downwardly projecting shoulder ea from the roof of' the kiln structure. The tiles e are formed with a. plurality of longitudinal channels e' each opening directly to the goods space'at its upper end and opening vto the goods space adjacent its lower'end through a lateral port e2.

As those skilled in the art will understand, the combustion chamber wall tiles e are of the type commonly used in forming the inner walls of the combustion chambers of Dressler tunnel vkilns and serve two special purposes, namely, to augment and direct the convection current circulation of the kiln atmosphere, and to minimize the transfer of heat to the `goods by radiation from the combustion chamber walls. Where more heat radiation to the goods from the combustion chamber walls, or a less pronounced convection circulation of the kiln atmosphere, is desirable, thev tiles e of Figs. -1-and 2 may be replaced by the thin verticallycorrugated wall plates eb, shown in Figs. 3 and 4. vThe tiles e and eb, may well be' formed of ceramicmaterial such as siliconcarbide which is not only suitably resistant, to high temperatures, but has a relatively high heat conductivity at the temperatures to which the combustion chamber wall tiles are subjected.

The highly heated products of combustion which issue from the combustion chambers through the ports H enter the car channels C4 and pass from the latter through the openings C5 in the car platforms C into contact with the bottom portions of the goods stacks on the car platforms. The gases passing out of the combustion chambers through the ports H, thus have a greater heating effect on goods ata low goods space level, than on goods at a higher level. 'I'he goods to y circulation ofthe kiln atmosphere, and particularly the portion of that circulation comprising the upflow through the channels e' in the tiles e, collectively tend to a greater heating of the upper level goods than of the lower level goods. By simple adjustment of the various dampers I. IA, and IB, it is possible to regulate the low level heating effect of the gases discharged through the heating action on thev goods space,

bustion chambers .at the sidesofthe heatinggsecf. Y, tion of va goods space through which goods are ports H, as required to insure asuitably uniform the goods at diilerent levels in ference between 'the temperatures at different preheating section levels.

As previously stated, atmospheric air may be passed into admixture with the heating gases which come;into contact with the goodsin the l kiln. v'I'he air so admitted modies the goods heatingaction in the of the kiln, and also prevents that action from being excessively rapid and the atmosphericair admitted also serves to make the atmosphere in the preheating section an oxidizing` atmosphere, which is especially desirable in some ceramic tiring operations. 'As shown, a channel A13 for'the inflow of atmospheric air, is formed preheating section of the in the kiln structure at each side'of the kiln'I chamber. As shown, each channel A13 opens into a lateral venlargement of the kilnchamber adjacent and at the outlet side of the corresponding damper I. The air thus introduced may be regulated in amount by theuse of an obturator A14 of suitable size inserted in and partially obstructing the outer end of each channel A13.

The heating up action in the preheating section of the kiln may also be reduced by reducing the extent to which the heating gases discharged from the combustion chambers are allowed to come into contact with, and heat the goods moving through the preheating section of the kiln. 'I'he heating effect in the preheating section may thus be reduced 'iby withdrawing a large portion of the heating gases from the portion of the goods space adjacent the junction of heating and preheating sections of the kiln, asv by drawing the gases through the ports AI nearest to the vheating section A2.

While in accordance vwith statutes, I have illustrated and described the best forms of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form ofthe apparatus disclosed without departing-from the spirit of my invention asset forth i-n the appended -claims and that in some cases certain featuresv of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is: 1. In the operation of a continuous tunnel kiln including a preheating section adjacent one end, a cooling section adjacentthe other end and an intermediate heating section and having combustion chambers at the sides of the heating` section of .a goods space through which goods are moved from one end of the kiln to the other, the method of regulating the relative temperatures to which the portions of the goods moving through the goods space at diierent levels are heated, which consist in passing heating gases from each combustion chamber at one end thereofinto the preheating section heatinggases from the combustion chamber at points distributed along the length of its lower` portion, into contact with the goods adjacent the bottom level of said space, and withdrawing heating gases from a portion of said preheating section displaced longitudinally' of the kiln from said heating section.l

2. In the operation o f a continuous` tunnel kiln including a preheating section adjacent one end, a cooling section adjacent the other end and an intermediate heating section and having comor ,tofprovide some definite difthe provisions of the,

of the goods space, passing moved from one end of the kiln to the other, the method of regulating the relative temperatures lto 'which vthe portions of thev goods moving through the goods space at different llevels arepassing heating gases from the combustin chamber at points distributed along the length of its lower portion into contact with the goods adjacent the bottom level of said space, withdrawing heating gases from ,a portion of said preheating section displaced longitudinally of the kiln froml said heating section, and passing cold air into the goods space adjacent the junction oi said heating and preheating sections.

3. In a continuous tunnelkiln having`a goods space and means for moving goods through said space lfrom one end of the kiln to the other, the combination with an elongated combustion chamber at each side of the goods space extendalong a heating sectionv of said space and hav-V ing an end voutlet adjacent one end of said section and having bottom outlets distributed along. the length of the combustion chamber and communicating with and adapted to discharge heating gases into the goods space adjacentv the vbottom of the latter, means for withdrawing` heating gases from a second section of the goods space, displaced longitudinally from the heating section, but adjacent the said end of the latter,

burners opening into the combustion chambers,4 and damper means for regulating the relative.

amounts of heating gas' discharged from each combustion chamber through its end and bottom outlets.

4.|In a continuous tunnel kiln .having a goods space and means for moving goods through said. space from one end of the kiln to theother, the combination with an elongated combustion chamber at each side of the goods space'extending along a heating section of said space and having outlets distributed along the length of the combustion chamber and communicating with and adapted to discharge heating gases into the goods space adjacent the bottomy of the latter; other means for the discharge of heatinggases from each combustion chamber, means for withdrawand channels beneath said platform and ports in the platform through which said channels communicate with the goods space above the platform, the combination with an elongated co'mbustion chamber at each side of the goods space extending along a heating section of 'said space andhaving an outlet adjacent one end of said section and having other outlets distributed along vthe length of the combustion chamber and communicating with andadapted t'o discharge heating heating gases from a second section of the goods space displaced longitudinally from the ing gases into said channels, means for WithdraweachI combustion goods space, each combustion chamber having an outlet to the goods space adjacent the junction oi' the preheating and heating sections and having one or more other outlets and communicating with the goods space adjacent the bottom level of the latter, and at a distance from said junction, means for effecting combustion in said goods space, means for withdrawing heating gases from the kiln in part, at least, from a portion of the goods space at a distance from said junction; adjustable damper means op regulating the relative amounts of heating gases passing through the iirsi; mentioned outlet and passing through 10 said other outlet Aor outlets of-each combustion chamber, and means for supplying cold air to the. goods space adjacent said junction. l

PHILIP DI-IUQ DRESSLER. `15 

